2018/05/02 by Jeon, K. -R., Ciccarelli, C., Kurebayashi, H. +5 · 1 citation
#FOS: Physical sciences #Mesoscale and Nanoscale Physics (cond-mat.mes-hall)
paper · doi:10.48550/arxiv.1805.00730
We quantify the spin Hall angle θSH and spin diffusion length lsd of Nb from inverse spin-Hall effect (iSHE) measurements in Nb/Ni80Fe20 bilayers under ferromagnetic resonance. By varying the Nb thickness tNb and comparing to a Ni80Fe20/Pt reference sample, room temperature values of θSH and lsd for Nb are estimated to be approximately -0.001 and 30 nm, respectively. We also investigate the iSHE as a function of temperature T for different tNb. Above the superconducting transition temperature Tc of Nb, a clear tNb-dependent T evolution of the iSHE is observed whereas below Tc, the iSHE voltage drops rapidly and is below the sensitivity of our measurement setup at a lower T. This suggests the strong decay of the quasiparticle (QP) charge-imbalance relaxation length across Tc, as supported by an additional investigation of the iSHE in a different sample geometry along with model calculation. Our finding suggests careful consideration should be made when developing superconductor spin-Hall devices that intend to utilize QP-mediated spin-to-charge interconversion.